fixed template.sh for parallel make

If the user runs `make` with `-j N` (N > 1), all three tasks in
textbin/Makefile.am that run template.sh will be run in parallel. Since
this script doesn't run atomically, the same functions end up being
added to the code multiple times, resulting in a compilation error.
Ignored generated files for textbin

Generated files should be ignored so as to avoid users inadvertently
checking them into VCS.
Made README.md consistent with lib/lib.mk

It was stated that `make show-html` should be used, but that task is
not defined. `make show` is the proper one to use.